Switch from abiword to unoconv for better import/export

pica-etherpad/Dockerfile

@@ -51,6 +51,7 @@ RUN curl -SL https://github.com/ether/etherpad-lite/archive/${ETHERPAD_VERSION}.
         ep_set_title_on_pad \
         ep_subscript_and_superscript \
         ep_tables2 \
+	ep_unoconv \
         ep_user_font_size && \
     git clone https://framagit.org/DeBugs/picasoft-etherpad-landing-page.git src/templates/picasoft-etherpad-landing-page && \
     rm package-lock.json && \
@@ -73,7 +74,7 @@ FROM base
 
 COPY entrypoint.sh /opt/etherpad-lite/entrypoint.sh
 RUN apt-get update && \
-    apt-get install -y mysql-client abiword && \
+    apt-get install -y mysql-client unoconv libreoffice-writer libreoffice-pdfimport && \
     chmod +x /opt/etherpad-lite/entrypoint.sh && \
     mkdir -p /opt/etherpad-lite && \
     chown -R node /opt/etherpad-lite && \